Why Did My Basement Floor Drain Back Up? 

A basement floor drain back up is almost never caused by a clog in the basement floor drain itself. In every home, the basement floor drain connects to the main drain line. Clogs in this main drain line almost always cause the floor drain to back up.

Liquids always take the path of least resistance. Because the basement floor drain is the lowest opening in the home’s drainage system, sewage and water coming up from the basement floor drain is a sign that the home’s main drain line is clogged. Main drain line clogs cause 99% of floor drain backups.

What causes a main drain clog?


      • How do they get in the main drain line?
        • Trees are pretty incredible: a tree can grow on the side of a cliff. What’s not incredible is finding out that you have tree roots in your sewer line. Roots naturally grow towards any moisture. So, if there are any cracks or weak points in your drain line, roots will find their way in.

          Cleaning The Main Drain Line

          • Cleaning your sewer line with a hydro jetter is always your best bet. The hydro jetter keeps the roots away for 5 to 7 years.
          • The auger is also a great tool for removing roots from your home’s sewer main. However, the auger doesn’t get all of the roots out of the drain line. Because of this, they will come back much faster.
          • Roots can damage the home’s main drain line. These roots can crack and eventually collapse a sewer line. To learn more about roots, check out our blog on roots in a sewer line.
This picture shows what it looks like then a plumber uses a drain machine to remove roots from a sewer line.
This picture shows what it looks like then a plumber uses an auger to remove roots from a sewer line.

Deteriorated Pipe

  • Why does an old sewer main/main drain line clog more?
    • Your home’s main drain is like anything else (except honey), it has an expiration date. As it starts to get closer to that expiration date, you can experience more frequent main drain clogs and therefor basement floor drain backups.
        • Overtime, scale and debris builds up on the inside of the pipe’s walls. If the main drain is made out of cast-iron, it will rust.
          • As the inside walls of the pipe rusts, the pipe becomes smaller and smaller. This decreases the amount of liquid that can flow through the pipe. If the main drain is given more than it can handle, it will come up through the basement floor drain.
          • This rust and build up is also extremely rough. Anything soft has the possibility to stick to the pipe’s walls, kind of like Velcro.

            What are some solutions?

            • Jetting
              • A hydro jetter uses high pressure water to blast the scale, rust, and debris off the main drain’s walls.
              • The high volume of water helps flush all of the gunk and nastiness out of the main drain line.
            • Lining and Replacement
              • Pipe lining or trenchless sewer replacement is a good way to replace the pipe without digging. This is great when digging is not feasible or desired. Digging up and replacing the pipe is usually less expensive than pipe lining but requires digging a large trench.

Break or Separation in The Home Main Drain Line

  • A break or separation in the main drain line is worst case scenario. This is by far the most expensive and requires a costly pipe lining or replacement. The broken section is the only part that needs to be replaced, but many times homeowners will choose to replace the entire line.

Bellies in The Main Drain Line

  • A belly is a flat spot or dip in the main drain line. This can happen over time as the ground settles.
    • How do you fix a belly in a sewer line?
      • The only way to fix a belly is to dig it up and replace it.
      • Routine preventative jetting will not fix the belly but can prevent unexpected clogs. Many people choose to go this route, because it is much less expensive than a full sewer replacement.

Abuse – Flushing More Than Your Main Drain Line Can Handle

  • This is the most common cause of floor drain backups. The best way to avoid an unexpected clogged is to be careful about what you flush down your toilets. Try your best not to flush paper towels, baby wipes, and feminine hygiene products.

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